Influence of preparation method on structure and properties of bulk nanocrystalline nickel

The nanocrystalline nickel powder prepared by high energy ball milling ( HEBM) and arc plasma evaporation ( APE ) method was consolidated into bulk specimens by pre-press sintering. The microstructure, porosity, hardness and compression strength of the bulk nanocrystalline nickel prepared by different methods were investigated. The results show that the evaporated bulk nanocrystalline nickel samples are easier to shape, and have higher density and thermal stability compared to the milled nickel samples because of evaporated nanocrystalline nickel powder is uniform, fine, globular and has small micro strain. The hardness of the evaporated bulk nanocrystalline nickel is higher and the compression yield strength ranging from 310 MPa to 410 MPa, the specimen exhibits lower sensitivity to strain rate and lower working hardening exponent. The damage mechanism of the evaporated bulk nanocrystalline nickel is intergranular fracture and grain boundary sliding mechanism plays an important role on the plastic deformation of the specimen.